From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9A8F2C4CEC4 for ; Wed, 18 Sep 2019 13:19:32 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 64E122067B for ; Wed, 18 Sep 2019 13:19:32 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 64E122067B Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id DDE8E6B02B0; Wed, 18 Sep 2019 09:19:31 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id D8F636B02B2; Wed, 18 Sep 2019 09:19:31 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id C7E5B6B02B3; Wed, 18 Sep 2019 09:19:31 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0212.hostedemail.com [216.40.44.212]) by kanga.kvack.org (Postfix) with ESMTP id A5D9D6B02B0 for ; Wed, 18 Sep 2019 09:19:31 -0400 (EDT) Received: from smtpin14.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with SMTP id 0FA46180AD802 for ; Wed, 18 Sep 2019 13:19:31 +0000 (UTC) X-FDA: 75948098142.14.bomb29_701056495ee18 X-HE-Tag: bomb29_701056495ee18 X-Filterd-Recvd-Size: 2861 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by imf16.hostedemail.com (Postfix) with ESMTP for ; Wed, 18 Sep 2019 13:19:29 +0000 (UTC) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 043BE1000; Wed, 18 Sep 2019 06:19:29 -0700 (PDT) Received: from localhost.localdomain (entos-thunderx2-02.shanghai.arm.com [10.169.40.54]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id A36493F575; Wed, 18 Sep 2019 06:19:23 -0700 (PDT) From: Jia He To: Catalin Marinas , Will Deacon , Mark Rutland , James Morse , Marc Zyngier , Matthew Wilcox , "Kirill A. Shutemov" , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Suzuki Poulose Cc: Punit Agrawal , Anshuman Khandual , Jun Yao , Alex Van Brunt , Robin Murphy , Thomas Gleixner , Andrew Morton , =?UTF-8?q?J=C3=A9r=C3=B4me=20Glisse?= , Ralph Campbell , hejianet@gmail.com, Kaly Xin , Jia He Subject: [PATCH v4 0/3] fix double page fault on arm64 Date: Wed, 18 Sep 2019 21:19:11 +0800 Message-Id: <20190918131914.38081-1-justin.he@arm.com> X-Mailer: git-send-email 2.17.1 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: When we tested pmdk unit test vmmalloc_fork TEST1 in arm64 guest, there will be a double page fault in __copy_from_user_inatomic of cow_user_page. As told by Catalin: "On arm64 without hardware Access Flag, copying from user will fail because the pte is old and cannot be marked young. So we always end up with zeroed page after fork() + CoW for pfn mappings. we don't always have a hardware-managed access flag on arm64." Changes v4: introduce cpu_has_hw_af (Suzuki) bail out if !pte_same (Kirill) v3: add vmf->ptl lock/unlock (by Kirill A. Shutemov) add arch_faults_on_old_pte (Matthew, Catalin) v2: remove FAULT_FLAG_WRITE when setting pte access flag (by Catalin) Jia He (3): arm64: cpufeature: introduce helper cpu_has_hw_af() arm64: mm: implement arch_faults_on_old_pte() on arm64 mm: fix double page fault on arm64 if PTE_AF is cleared arch/arm64/include/asm/cpufeature.h | 1 + arch/arm64/include/asm/pgtable.h | 12 ++++++++++ arch/arm64/kernel/cpufeature.c | 6 +++++ mm/memory.c | 35 ++++++++++++++++++++++++----- 4 files changed, 49 insertions(+), 5 deletions(-) -- 2.17.1